New study shows conversion of grasslands to agriculture in Southeastern Minnesota contributes to groundwater nitrate contamination

Research from the University of Minnesota and the Natural Capital Project predicts contaminated wells likely to increase by 45 percent in the near future

July 10, 2014

Conversion of grasslands to agricultural fields across Southeastern Minnesota is increasing groundwater nitrate contamination in private drinking water wells according to a new study by researchers with the University of Minnesota and the Natural Capital Project.

Writing in the journal Environmental Research Letters, the researchers outline the economic costs associated with groundwater pollution along with threats to overall water quality and ecosystem services.

“Households can dig a new well, purchase bottled water, or install a home nitrate-removal system, but dealing with a contaminated well is expensive and these costs are typically born entirely by private households,” said Bonnie Keeler, lead author and lead scientist with the Natural Capital Project at the University of Minnesota’s Institute on the Environment. “We found evidence that recent trends in grassland loss to agriculture between 2007 and 2012 are likely to increase the future number of contaminated wells by 45%, leading to millions of dollars in lost income and remediation costs for private households.”

The analysis focuses on eleven counties in Southeastern Minnesota — a region classified as highly vulnerable to groundwater contamination and having one of the highest rates of recent grassland conversion to agriculture in the state, but the results can also be extrapolated to regions across the Midwest U.S. undergoing rapid land conversion.

The researchers used publicly available well data and nitrate chemistry readings to predict how changes in land use will affect the likelihood of well contamination. The team also discovered a significant relationship between high-nitrate wells and nearby agricultural lands. Using this relationship, along with other soil and geologic information and well characteristics, they created a model that could be used to evaluate how recent trends in grassland loss to agriculture may affect the future number of contaminated wells in the region.

The Natural Capital Project is a partnership combining research innovation at the University of Minnesota’s Institute on the Environment and Stanford University with the global reach of conservation science and policy at The Nature Conservancy and the World Wildlife Fund.